Chloramination Techniques To Reduce NDMA
Formation During Disinfection
Author(s)
I. M. Schreiber & W. A. Mitch
Abstract
Previous studies modeled NDMA formation during chlorine disinfection as
arising from the oxidation of an unsymmetrical dimethylhydrazine intermediate
formed from the reaction of monochloramine and dimethylamine. However,
chlorination of wastewater effluents indicated that this mechanism could not
account for a significant portion of the observed NDMA formation. Laboratory
studies indicated that the order of reagent addition can have a significant effect
on NDMA formation. Important factors included the chlorination state of
organic nitrogen precursors and the formation of dichloramine. Disinfection
systems were devised that maximize the formation of chlorinated organic
nitrogen precursors and minimize dichloramine formation in order to minimize
NDMA formation. Preliminary results from pilot testing indicate the
effectiveness of these disinfection scenarios during chlorination of drinking
waters and wastewaters. Evidence for a new reaction pathway to explain NDMA
formation during chlorine disinfection is presented.
Keywords: chloramines, disinfection by-products, NDMA.
1 Introduction
As a result of the reduction in the allowable concentrations of trihalomethanes
(THMs) and haloacetic acids (HAAs) in treated drinking waters resulting from
the US EPA Disinfection Byproduct Rules, drinking water utilities are
considering switching to chloramine disinfection to minimize THM and HAA
formation. Increasing population densities are necessitating the use of
wastewater-impacted drinking water supplies that exhibit higher levels of
dissolved organic nitrogen (DON). In addition, the elevated levels of inorganic
nitrogen in wastewater effluents, together with those resulting from non-point
Keywords
chloramines, disinfection by-products, NDMA.
Related Book
Other papers in this volume
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